title: Inhibition of quorum sensing in Chromobacterium violaceum by Syzygium cumini L. and Pimenta dioica L.
abstract: OBJECTIVE
  To investigated into the anti-quorum sensing (QS) activity of Syzygium cumini L. (S. cumini) and Pimenta dioica L. (P. dioica) using Chromobacterium violaceum (C. violaceum) strains.
  
  
  METHODS
  In this study, anti-QS activity of ethanol extract of Syzygium cumini L. and Pimenta dioica L. were screened using C. violaceum CV026 biosensor bioassay. By bioassay guided fractionation of S. cumini and P. dioica, ethyl acetate fraction (EAF) with strong anti-QS activity was separated. Inhibition of QS regulated violacein production in C. violaceum ATCC12472 by EAF was assessed at different concentrations. The effect of EAF on the synthesis of autoinducer like N-acyl homoserine lactone (AHL) was studied in C. violaceum ATCC31532 using its mutant C. violaceum CV026 by standard methods.
  
  
  RESULTS
  EAF inhibited violacein production in C. violaceum ATCC12472 in a concentration dependent manner without significant reduction in bacterial growth. Complete inhibition of violacein production was evidenced in 0.75-1.0 mg/mL concentration of EAF without inhibiting the synthesis of the AHL. TLC biosensor overlay profile of EAF revealed two translucent spots in S. cumini and P. dioica that inhibited C6-AHL mediated violacein production in C. violaceum CV026.
  
  
  CONCLUSIONS
  This study indicates the anti-QS activity of the tested medicinal plants against C. violaceum.
authors.affiliation: Yenepoya Research Center, Yenepoya University, University Road, Nityananda Nagar, Deralakatte, Mangalore-575018, India.
authors.forename: Halkare Suryanarayana
authors.initials: HS
authors.lastname: Vasavi
authors.forename: Ananthapadmanabha Bhagwath
authors.initials: AB
authors.lastname: Arun
authors.forename: Punchapady Devasya
authors.initials: PD
authors.lastname: Rekha
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D015374:Biosensing Techniques / Q000379:methods; D002861:Chromobacterium / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D027841:Pimenta / Q000737:chemistry*; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D053038:Quorum Sensing / Q000187:drug effects*; D027842:Syzygium / Q000737:chemistry*
chemical_list: D054742:Acyl-Butyrolactones; D000900:Anti-Bacterial Agents; D010936:Plant Extracts
keywords: Anti-quorum sensing; Chromobacterium; Medicinal plants; Pathogenicity; Quorum sensing